Magnesium alloys in which various additive elements are incorporated into magnesium have been used as materials constituting various structural members, such as housings of mobile electric/electronic devices, e.g., cellular phones and laptop computers, and parts of automobiles.
Structural members composed of a magnesium alloy are mainly produced using a cast material (an AZ91 alloy specified in the standards of the American Society for Testing and Materials (ASTM)) formed by a die casting process or thixomolding process. In recent years, structural members produced by subjecting sheets composed of a wrought magnesium alloy, typified by an AZ31 alloy specified in the standards of ASTM, to press forming have started to be used. For example, Patent Literature 1 proposes a magnesium alloy sheet composed of an alloy corresponding to the AZ91 alloy specified in the standards of ASTM and having excellent press formability.
Since magnesium is an active metal, the surfaces of the structural members and the magnesium alloys constituting the structural members are generally subjected to anticorrosion treatment, such as anodic oxidation treatment or chemical conversion treatment.